DatabaseService that uses Copycat Raft to provide a strongly consistent and durable database.
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/WriteRequest.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/WriteRequest.java
new file mode 100644
index 0000000..7314e4f
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/WriteRequest.java
@@ -0,0 +1,93 @@
+package org.onlab.onos.store.service;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import java.util.Objects;
+
+/**
+ * Database write request.
+ */
+public class WriteRequest {
+
+ private final String tableName;
+ private final String key;
+ private final byte[] newValue;
+ private final long previousVersion;
+ private final byte[] oldValue;
+
+ public WriteRequest(String tableName, String key, byte[] newValue) {
+ this(tableName, key, newValue, -1, null);
+ }
+
+ public WriteRequest(String tableName, String key, byte[] newValue, long previousVersion) {
+ this(tableName, key, newValue, previousVersion, null);
+ checkArgument(previousVersion >= 0);
+ }
+
+ public WriteRequest(String tableName, String key, byte[] newValue, byte[] oldValue) {
+ this(tableName, key, newValue, -1, oldValue);
+ }
+
+ private WriteRequest(String tableName, String key, byte[] newValue, long previousVersion, byte[] oldValue) {
+
+ checkArgument(tableName != null);
+ checkArgument(key != null);
+ checkArgument(newValue != null);
+
+ this.tableName = tableName;
+ this.key = key;
+ this.newValue = newValue;
+ this.previousVersion = previousVersion;
+ this.oldValue = oldValue;
+ }
+
+ public String tableName() {
+ return tableName;
+ }
+
+ public String key() {
+ return key;
+ }
+
+ public byte[] newValue() {
+ return newValue;
+ }
+
+ public long previousVersion() {
+ return previousVersion;
+ }
+
+ public byte[] oldValue() {
+ return oldValue;
+ }
+
+ @Override
+ public String toString() {
+ return "WriteRequest [tableName=" + tableName + ", key=" + key
+ + ", newValue=" + newValue
+ + ", previousVersion=" + previousVersion
+ + ", oldValue=" + oldValue;
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(key, tableName, previousVersion);
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+ if (obj == null) {
+ return false;
+ }
+ if (getClass() != obj.getClass()) {
+ return false;
+ }
+ WriteRequest other = (WriteRequest) obj;
+ return Objects.equals(this.key, other.key) &&
+ Objects.equals(this.tableName, other.tableName) &&
+ Objects.equals(this.previousVersion, other.previousVersion);
+ }
+}